Dimethylsulphoxide (DMSO) is a known compound, a colourless oily liquid, for which a variety of physiologic properties have been described. For example, it has local analgesic and anti-inflammatory effects, is bacteriostatic, acts as a diuretic inducing a negative salt balance, has a tranquilising effect and potentiates the effects of other compounds. It is also an antianoxic and has been known to increase the hypoxic survival of rats. Furthermore, it appears to have therapeutic efficacy in the treatment of mental illnesses and rheumatic diseases.
A few investigations into the anti-viral properties of DMSO have been carried out. Remission of crinkle strawberry virus symptoms in Fragaria vesca resulted from spraying infected plants with 500 ppm DMSO containing 500 ppm of 6-mercaptopurine or 100 ppm of 6-methylpurine. Suppression of symptoms and a change in the syndromes of peach mosaic (PMV) and necrotic ringspot viruses (NRSV) resulted from injection of peach trees with DMSO. However, very mild forms of the viruses were subsequently found in the trees. Local lesion symptoms of tobacco mosaic virus (TMV) in several hosts were reduced by mixing 0.05 to 1% DMSO with virus before innoculation (The Sulphur Institute Journal, Autumn 1969, 2-6).
The effect of DMSO on the infectivity of four RNA and two DNA viruses has also been studied (Chan and Gadebusch, Applied Microbiology, vol. 16, no. 10, 1625-1626, 1968). At a concentration of 80% in buffered saline DMSO inactivated the infectivity of every virus tested. However, experiments designed to study the chemotherapeutic value of DMSO showed the compound to possess no beneficial effect when administered parenterally to mice infected with influenza A (PR-8) virus or Semliki Forest virus.
The stabilisation of enveloped viruses by DMSO has been studied (Wallis and Melnick, J. Virol. vol. 2, no. 9,953-954, 1968). These studies showed that concentrations of DMSO as low as 5% effectively protected the enveloped viruses under test against the trauma of freezing, i.e. the viruses were not inactivated by freezing. There was no suggestion that DMSO could be used therapeutically to combat infections attributable to enveloped viruses.